Factors affects the blood oxygen measuring

The followings may affect the blood oxygen measuring:

1. Wearing the watch too loosely. The back of the watch needs skin contact with your wrist for blood oxygen measurement.
2. Smudges or sweats on the back of the watch.
3. Arm and wrist movements during a measurement.
4. Cold temperature.
5. Wearing the watch too tightly affects the blood circulation, which makes the measurement inaccurate.
6. Permanent or temporary changes to your skin, such as tattoos on your wrist.